The EU's top political leaders meet three times a year in a rose-coloured marble building known as Justus Lipsius.

EU leaders arrived in gas-guzzling cars to debate green issues

It is named after a 16th-Century Dutch scholar often described, predominantly by his fans, as one of the most learned men of his day, as well as the founding father of neo-stoicism, which combined pagan materialism with Christianity.

Nowadays, the new Europe under Jose Manuel Barroso could even be described as eco-stoicism, combining materialism with environmental zealotry.

The new movement, though, does not have as many converts as the Portuguese boss of the European Commission would like.

His mission at this year's spring summit is to evangelise to those less enthusiastic parts of Europe, mostly in the East, about the merits of his ambitious energy and climate change package.

The key parts of that plan envisage:

slashing CO2 emissions by one fifth before 2020

having renewable sources such as wind, wave and biomass account for 20% of the total energy mix

separating power generation (the making of electricity or gas) from distribution (the manner in which it is transported through pipes or cables).

Mission to empower

So what's the rush?

In Europe at least, climate change is now generally agreed to be the planet's most pressing problem, in need of urgent action.

And no climate change solution is possible without changing the way we source, distribute or consume energy, in whatever form that takes.

It all follows what could only be described as an annus horribilis in European energy terms in 2006.

Jose Manuel Barroso is a green evangelist at the summit

First of all, Russia turned off the tap supplying gas through Ukraine, affecting millions of Europeans in the process.

Then the Commission raided some of Europe's key energy companies, suspected of colluding to keep wholesale prices artificially high.

As if that were not enough to sow worries about energy, later in the year the price of a barrel of oil soared to more than $75.

Finally, the year ended with blackouts which plunged much of Western Europe into darkness, caused by energy giants owning both the generation and distribution side of electricity.

So the EU needed a fixed energy policy to replace the ad hoc set of rules and agreements which had seen the continent muddle through over the previous decades.

But getting all 27 member states to agree to legally binding and quite bold sets of targets was never going to be easy. It could also divide Europe once again along East-West lines - a mere three years after reuniting it.

Pragmatism looms

That's especially true of the plan to have renewable sources, such as wind, wave and solar power, make up a fifth of Europe's energy mix.

Poland, for example, gets more than 95% of its electricity needs by burning coal - carbon in one of its purest forms - so it was always going to have difficulty meeting a legally binding target of 20%.

That doesn't bother Mr Barroso, who was stressing "solidarity" and "burden-sharing" when he spoke to me this week.

That would, in effect, mean that greener economies such as Sweden, Germany and Denmark would have to carry more of the responsibility than post-communist nations in the East.

Mr Barroso, however, is not exactly setting a good personal example when it comes to going green.

When he's not being chauffeur-driven from place to place in a large German limousine, the Portuguese former prime minister drives a VW Touareg 4x4, which belches out an astonishing 355g/km of CO2.

Embarrassing when you think that the commission he heads has just set legal targets of 120g of CO2 for all new cars from 2012.

Perhaps it was my reminding him of this fact that led him to walk from the commission's Berlaymont building to the Justus Lipsius complex across the road.

Some might call that a green footprint - others might describe it as eco-pragmatism.